Structural and thermal insights into the luminescent behavior of Dy³⁺-Doped BaZrO₃ with alkali metal codopants under UV radiation

Abstract

This study investigates the structural, thermal, and photoluminescent properties of Dy³⁺-doped BaZrO₃ (BZO) perovskites, synthesized via a co-precipitation method, incorporating alkali metal codopants (Li⁺, Na⁺, and K⁺). X-ray diffraction (XRD) analysis confirmed the retention of the cubic perovskite phase following doping, with Rietveld refinement further revealing minor lattice distortions due to Dy³⁺ incorporation. The Williamson-Hall (W–H) analysis revealed average crystallite sizes of 53 nm and 66 nm for undoped and 0.01 Dy³⁺-doped BaZrO₃, respectively, with corresponding micro-strain values of 1.79 × 10⁻³ and 1.81 × 10⁻³, suggesting lattice distortions due to incorporation of Dy³⁺. Fourier transform infrared (FTIR) spectroscopy confirmed the cubic perovskite structure and subtle structural modifications upon doping. Notably, the absence of moisture-related peaks highlights the effectiveness of the synthesis process, including rigorous drying and calcination steps that prevented hydrous species. Photoluminescence (PL) analysis of Dy³⁺-doped BaZrO₃ exhibited three prominent emission peaks at 452 nm, 573 nm, and 656 nm under 368 nm excitation. These peaks correspond to the characteristic intra-4f electronic transitions of Dy³⁺ ions, specifically, ⁴I_13/2 to ⁶H_15/2, ⁴F_9/2 to ⁶H_13/2, and ⁴F_9/2 to ⁶H_11/2, representing blue, yellow, and red emissions, respectively. Photoluminescence decay studies showed multi-exponential behavior, with the average lifetime decreasing from 641 μs in undoped BZO to 492 μs in Dy³⁺-doped samples attributed to enhanced non-radiative recombination pathways. Among the codopants, Li⁺ demonstrated the most significant improvement in luminescence intensity and thermal stability by mitigating defects and optimizing charge compensation.